ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus GmbHGöttingen, Germany10.5194/acp-7-5937-2007Spectral absorption properties of atmospheric aerosolsBergstromR. W.1PilewskieP.2RussellP. B.3RedemannJ.4BondT. C.5QuinnP. K.6SierauB.71Bay Area Environmental Research Institute, Sonoma, CA, USA2Laboratory for Atmospheric and Space Physics, Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA3NASA Ames Research Center. Moffett Field, CA, USA4Bay Area Environmental Research Institute, Ventura, CA, USA5University of Illinois, Champaign-Urbana, IL, USA6Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, Washington, USA7Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland0412200772359375943This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article is available from http://www.atmos-chem-phys.net/7/5937/2007/acp-7-5937-2007.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/5937/2007/acp-7-5937-2007.pdf

We have determined the solar spectral absorption optical depth of
atmospheric aerosols for specific case studies during several field programs
(three cases have been reported previously; two are new results). We
combined airborne measurements of the solar net radiant flux density and the
aerosol optical depth with a detailed radiative transfer model for all but
one of the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX,
INTEX-A) contained aerosols representing the major absorbing aerosol types:
pollution, biomass burning, desert dust and mixtures. In all cases the
spectral absorption optical depth decreases with wavelength and can be
approximated with a power-law wavelength dependence (Absorption Angstrom
Exponent or AAE). We compare our results with other recent spectral
absorption measurements and attempt to briefly summarize the state of
knowledge of aerosol absorption spectra in the atmosphere. We discuss the
limitations in using the AAE for calculating the solar absorption. We also
discuss the resulting spectral single scattering albedo for these cases.